Join monthly data to daily data

Hello and thank you for any assistance.

Please see node annotation in image below and the associated workflow I have attached.

Straight forward/probably simple - I am just learning sort of.

Here is what annotation says (in case my image above does not come through):

Table A is data by day of each month.

Table B is data by each month (not daily).

How can I join these so that I get data only once for each year/month match, not for every day?

Thanks again for any assistance.

Help.knwf